Bump to v4.0.0.

internal/stackGet.js

@@ -0,0 +1,20 @@
+define(['./assocGet'], function(assocGet) {
+
+  /**
+   * Gets the stack value for `key`.
+   *
+   * @private
+   * @name get
+   * @memberOf Stack
+   * @param {string} key The key of the value to get.
+   * @returns {*} Returns the entry value.
+   */
+  function stackGet(key) {
+    var data = this.__data__,
+        array = data.array;
+
+    return array ? assocGet(array, key) : data.map.get(key);
+  }
+
+  return stackGet;
+});